Apparatus for producing cigarette filters

ABSTRACT

A machine for making cigarette filters of the type within which sections of fibrous and of free-running filter materials are arranged in succession and which has a filler head for feeding free-running filtration material into spaces situated between filter elements or wads arranged on a filter-tip cover strip with which the wads travel continuously forwards, a storage container being provided, the discharge slot of which container constitutes the filling aperture is characterized by the provision of shutoff arrangements operating in conjunction with the discharge slot in the filler head so as to regulate the opening of that slot, and by the fact that the bottom portion of the storage container is made cylindrical and the shut-off arrangements consist of a scoop-shaped closing member, in contact with the inner face of the cylindrical member and capable of rotation about the longitudinal axis thereof.

Burrus et al.

[ Nov. 20, 1973 APPARATUS FOR PRODUCING CIGARETTE FILTERS lnventors: Charles Burrus, Boncourt; Serge Boegli, Zurich, both of Switzerland Assignee: F. D. Burrus & Cie, Boncourt,

Switzerland Filed: Oct. 5, 1971 Appl. No.: 186,669

[30] Foreign Application Priority Data Dec. 1, 1970 Switzerland 17754/70 [52] U.S. Cl. 93/1 C, 93/77 FT [51] Int. Cl A24c 5/50, B29d 23/00 [58] Field of Search 93/1 C, 77 FT, 84 TW, '93/93 l-lT; 214/17 C [56] References Cited UNITED STATES PATENTS 3,357,321 12/1967 Hall 93/1 C 3,610,112 10/1971 Labbe 93/1 C 3,623,404 11/1971 Jackson 93/1 C 2,661,876 12/1953 Kindseth 222/558 T Primary Examiner-Andrew R. Juhasz Assistant ExaminerLeon Gilden AttorneyPierce, Scheffler & Parker [5 7 ABSTRACT A machine for making cigarette filters of the type within which sections of fibrous and of free-running filter materials are arranged in succession and which has a filler head for feeding free-running filtration material into spaces situated between filter elements or wads arranged on a filter-tip cover strip with which the wads travel continuously forwards, a storage container being provided, the discharge slot of which container constitutes the filling aperture is characterized by the provision of shut-off arrangements operating in conjunction with the discharge slot in the filler head so as to regulate the opening of that slot, and by the fact that the bottom portion of the storage container is made cylindrical and the shut-off arrangements consist of a scoop-shaped closing member, in contact with the inner face of the cylindrical member and capable of rotation about the longitudinal axis thereof.

9 Claims, 9 Drawing Figures PATENTED NOV 2 0 I975 SHEET 10? 5 Fig.1

PMENIEUmvza ms 37,72,967

PATENTED NOV 2 0 I975 SHEET 3 OF 5 PATENTED REV 20 \975 SHEET BF 5 APPARATUS FOR PRODUCING CIGARETTE FILTERS The object of the present invention is a device for the manufacture of cigarette filters within which sections of fibrous and of free-running filter materials are arranged in succession and which has a filler head for feeding free-running filtration material into spaces situated between filter elements or wads arranged on a filter-tip cover strip, with which the wads travel continuously forwards, a storage container being provided, the discharge slot of which constitutes the filling aperture.

In one known device for making multiple filters, individual filter sections are attached, spaced apart, to a cover strip, which is wrapped partly round them, and then a free-running filtering medium is discharged from a filling hopper into the spaces between the filter sections. By regulation of the depth of the filter material in the hopper, it is sought to regulate the pressure of that material in the base of the hopper and hence the degree to which the said spaces are filled. The drawback of this device is that the degree of filling can scarcely be controlled by the depth of filter material in the hopper, because the resistance between the individual particles of filter material and also between these and the hopper walls is far too great for the depth of filter material to have such influence. Another disadvantage of this device is that the discharge aperture of the filler head cannot be closed when the machine is at a standstill, so that especially when running faults occur, which often require the filler head to be removed free-running filter material runs out and soils the device.

The purpose of the invention is to provide a device free from these drawbacks.

The device here proposed is characterised by the provision of shut-off arrangements operating in conjunction with the discharge slot in the filler head so .as to regulate the opening of that slot, and by the fact that the bottom portion of the storage container is made cylindrical and that shut-off arrangements consist of a scoop-shaped closing member, in contact with the inner face of the cylindrical member and-capable of rotation about the longitudinal axis thereof.

To improve the regulation of the discharge slot, it is desirable for the closing edge of the closing member to run helically about the longitudinal axis of the cylindrical portion of the storage container, so that when the closing member turns in the closing direction it is initially the end of the dischargeslot that faces the opp'o- 7 site way to the direction of travel of the spaces to be filled which is freed, this being followed by those parts of the discharge slot which are farther from the said end thereof as the closing member continues to turn. It is desirable for the device here proposed to incorporate means of providing a continuous supply of a succession of filter elements or wads, uniformly spaced, on the continuously fed filter-tip cover strip; means of securing the individual filter wads to the cover strip; means of guidance and conveyance for guiding the cover strip and its attached filter wads and continuously moving them forwards; a shaping member, in the vicinity of the said means of guidance and conveyance, by which the cover strip, as it moves forward, is wrapped at least approximately U-fashion round the filter wads attached to it; a sliding member above the means of guidance and conveyance, such as to lie, be-

tween the arms of the U-shaped cover strip, in contact with the tops of the filter wads moving forward with the latter, this sliding member being provided with the discharge slot of the filler head; a guide by which the cover strip or an additional strip is formed into a tube completely enclosing the filter wads and the spaces between them filled with free-running filter material, with the edges of the cover strip or additional strip overlapping; means of joining together the overlapping edges; and means whereby the tube filled with sections consisting of filter wads and free-running filter material can be divided into sections of given length.

It is also desirable for the filler head to have an elongated sliding member extending in the direction of travel of the filter wads and having a sliding face in such close contact as to form a seal with the tops of the filter wads moving forward with the cover strip; for the width of the sliding member to be at least approximately equal in diameter to the filter wads to be wrapped in the cover strip; and for the side faces of the sliding member to be parallel to each other and to the direction of travel of the cover strip and to be designed to lie'in such close contact as to form a seal with those faces of the arms of the U-shaped cover strip which face towards each other The invention is explained hereunder by way of example, in' conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic side elevation of a device for producing a cigarette filter unit;

FIG. 2 is a section through the filler head, along the line 11-11 in FIG. 3; l

FIG. 3 is a section along the line IlllII in FIG. 2;

FIG. 4 is an enlarged section along the line IV-IV in FIG. 2; Y I

FIG. 5 is a section along the line V-V in FIG. 1, to show the fixing mechanism;

FIG. 6 is a section along the line VI-VI in FIG. 1, to show the top welding arrangements; FIG. 7 is a section along the line VII-VII in FIG. 1, to show the cooler;

FIG. 8 is a section along the line VIII-VIII in FIG. 1, to show the bottom welding arrangements; and FIG. 9 is a longitudinal section of the adjusting mechanism serving to bring the operating-cycle of the filter elementfeed into line with that of the cutting mechanism.

In the equipment shown in way of example in FIG. 1, the arrangements for continuously feeding a succession of uniformly spaced and axially aligned filter wads, l

and 2, on to a continuously fed filter-tip cover strip, 3,

, include a machine, 4, known in the cigarette industry as a Molins D.A.P.T.C. Machine, which is described in detail in U.S.A. Pat. Specification No. 2,957,285. This machine 4 has two magazines, 5, for holding lengths of filter material, such as cellulose and acetate, for example, and two rotary drums, 6, which serve to receive them. The machine 4 is worked by the driving chain 7.

Round their periphery, the drums 6 contain grooves,

mechanism, 8, by which the wads l and 2 are alternately fed forwards in axial alignment, in the direction of the arrow 9, and simultaneously spaced uniformly apart.

Next, the uniformly spaced and axially aligned filter wads l and 2 are fed continuously to a filter-tip cover strip, 3, likewise continuously fed, on which they are deposited, being guided at the sides, as shown in FIG. 5, by the guide members and 11 and held in place, in relation to one another, by a pressure band, 12, situated above and running round in synchrony with the cover strip 3.

That face of the cover strip 3 which lies towards the filter wads 1 and 2 is coated with an adhesive such as, for instance, a thermoplastics, which softens under the action of heat, so that it is possible for the individual filter wads l and 2, directly they have been discharged on to the cover strip 3, to be secured to it with the aid of a heater, 13, thereby preventing relative motion, that is to say preventing any alteration in their spacing. As can be seen from FIG. 5, the cover strip 3 rests on a support, 14, while the heater 13 can be pressed from below, through a slot in the support 14, against the cover strip 3 and thus indirectly against the filter wads l and 2 that require to be anchored in place. The temperature of the heater 13 should preferably be thermostatically controlled. The heater 13 is so arranged that it can be moved clear of the cover strip 3 when this is stationary, to avoid burning it.

The individual filter wads 1 and 2 having been secured to the cover strip 3, the latter is fed on to an endless conveyor belt, 15, these parts being fed jointly on to a guide track that functions as a shaper, on which the cover strip 3, as it moves forward, is wrapped round the filter wads l and 2 attached to it, so as to form at least approximately a letter U. This assembly is then carried by the conveyor belt 15 to a filler head, 16, shown in greater detail in FIGS. 2, 3 and 4, which serves for the introduction of free-running filter material such as charcoal, for example, into the space 17 formed between the individual filter wads l and 2. The downward-facing discharge end of the storage container 18 of the filler head 16 is connected to a sliding member, 19, which is in contact with the wads l and 2 and encloses them to the extent of at least 180. The width of the sliding member 19 is approximately equal to the diameter of the filter wads l and 2 it is desired to wrap in the cover strip 3, the side faces 19a and 19b running parallel to each other and to the direction of motion of v the conveyor belt 15 and serving to provide sealing contact with the inner faces 30 and 3b of the U-arms of the cover strip 3. In this way, spaces bounded by the end faces of the filter wads l and 2, the cover strip 3 and the sliding surface of the sliding member 19 are formed at 17.

In order to promote complete filling of the spaces 17 and the follow-up flow of the filter material in the container 18 down through the discharge slot 20, the filler head 16 is equipped with a vibrator, 23, the effect of which is to cause the tiller head 16, mounted resiliently on flat springs (24, in FIG. 3), to vibrate at 100 cycles per second in a vertical plane.

The filler head 16 is suspended by the springs 24 from a guide, 26, which runs parallel to the track 25 provided for the conveyor belt 15, and clamped to the said guide by means of screws, 27. The screws 28 serve for horizontal alignment of the sliding member 19 in relation to the filter wads l and 2 below it, while the screws 29, rigidly connected to the guide 26, enable the amplitude of vibration of the filler head 16, imparted by the vibrator 23, to be regulated.

Since the width of the sliding member 19 is approximately equal to the diameter of the filter wads, the discharge slot 20 can be made relatively broad, this being very important for unhindered follow-on of the freerunning filter material. At the end of the discharge slot 20 is a semi-circular trimming edge, 30, which bounds the cross-section of the filter wads l and 2 as they pass through and trims off the excess of free-running filter material. This trimming edge 30, being exposed to heavy wear when the equipment is running, is provided on an interchangeable trimmer, 31, which can be inserted into the sliding member 19.

The underside of the trimmer 31 is provided with transverse grooves, 31a, which remove any grains of the free-running filter material that still remain on the filter wads, pick them up and release them into the succeeding spaces 17.

Because, when certain free-running filter materials are used for filling, an undesirable amount of dust arises, which is deposited on the upper face of the filter wads and darkens them, the trimmer 31 may also be equipped with a suction aperture, through which the dust coating can be removed by the creation of a very slight partial vacuum.

The enable the size of the discharge slot 20 to be adapted to the particle size of the free-running filter material, the bottom portion, 32, of the storage container 18 is made cylindrical. Within this bottom portion is a scoop-like closing member, 33, in sliding contact with the interior face of the cylindrical member 32 and designed to turn about the longitudinal centre line thereof. For rotating the closing member 33, there is a handle, 34, while a stud, 36, thrust by a spring towards the semi-circular plate 35, can drop home into recesses in various positions on the plate 35. The closing member 33 is thus shaped like a section of the curved surface of a cylinder and is made as thin as possible, so as to keep to the minimum the force that needs to be exerted on the handle 34 to move the closing member when the container 18 is full. The closing edge of the closing member 33, moreover, is also made oblique or sharpened in relation to the inner face of the cylindrical member 32, so as to facilitate movement of the closing member 33, and it runs helically round the longitudinal axis 37 of the cylindrical member 32, so that as the closing member 33 is turned in the direction for opening, it is initially the end of the discharge slot 20 that faces the opposite way to the direction of travel of the spaces to be filled which is freed, this being followed by those parts of the discharge slot 20 which are farther from the said end thereof as the closing member continues to turn.

There is also advantage in thus being able to close the discharge slot 20 when the running of the installation is interrupted or when the clamping screws 27 are released and the filler head 16 is removed to expose the cover strip 3 that lies below and carries the filter wads land 2.

To prevent the storage container 18, which is fed from the reserve container 38 (FIG. 1), from being over-filled, it is entered by two lengths of pipe, 39, each with its top end joined to a feed pipe, 40, for the freerunning filter material, and with its bottom end situated at the filling level of the container 18. In the example illustrated, the pipe 39 nearer to the suction aperture 22 contains a cutout, 41, facing towards the suction aperture, to increase the outflow of filter material, the consumption of which is greatest at that point. To cut off the supply of filter material from the reserve container 38, the storage container 18 is also provided with a shutter, 42, which can be slid across the lower ends of the feed pipes 40. 7

In the terminal portion 43 of the sliding member 19, the upper part 44 of the track 25 is. so shaped that the cover strip 3 is converted into a complete tube, a suction device being provided at 45 for the removal of any free-running filter material remaining between the edges of the cover strip.

Forjoining together the now overlapping edges of the cover strip, there now follows a sealing unit, 46, which, as shown in FIG. 6, has a heatable element, 47, which can be applied to the tube that is to be sealed. To prevent any of the free-running filtermaterial, in filter tips fitted to cigarettes, from finding its way between the outside of the filter wads and the inside of the cover strip and into the smokers mouth, the cover strip should be stuck to the filter wads round their entire periphery.

To that end, the heatable element 47 is provided with a guidance channel, 48, semi-circular in section, its radius of curvature being the same as the outside radius of the tube that is to be produced. To achieve precision in the diameter of the tube produced, the guidance channel 48 in the heatable element 47 is immediately followed by another such channel, 49, in a cooling unit, 50, which can be lowered on to the tube so as to cause the heat-softened plastics to set.

When the tube has been stuck together, it is passed to a cutting head, 51, in which it is divided up in such a way that the length of each filter assembly is six times the length of a filter for a cigarette.

As the cutting head 51 must be precisely synchronised with the movement of the filter wads within the finished tube, a timing mechanism, 52 (FIG. 9), is also provided, to synchronise the machine 4 feeding the filter wads 1 and 2 on to the cover strip 3 with the drive of the cutting head 51 by which the tube filled with filter material is divided into given lengths.

The drives of the feed mechanism 4 and that of the cutting head 51 are linked together by a two-part shaft, 53a/53b. Between the first part 53a and the second part 53b of the connecting shaft is an adjusting member, 54, which rotates with the latter, for altering the relative angular position of the two parts 53a and 53b of the shaft.

The adjusting member 54 has two parts, 55 and 56,-

in axial alignment, which can slide axially in relation to each other, the part 56 bearing guides, 57, which engage in helical grooves, 58, in the other part, 55.

To shift part 56 of the adjusting member in the axial direction c in relation to the other part 55, a spindle, 59, driven by an electric motor, is provided, which in rotating displaces the intermediate member 60 and hence also the part 56.

Beyond the cutting head 52 is another adhesive joining unit, 61 (FIGS. 1 and 8), in which the heater 62 bears against the tube from underneath. The guide channel 63 in this heater is semi-circular in section and cements the as yet uncemented part of the cover strip 3 formed into a tube to the filter wads 1 and 5, so that these adhere to the cover strip 3 round their entire periphery and no free-running filter material can escape from the spaces 17, between the faces of the wads and the strip 3. Endless spiral wires, 64, run round and exert pressure on the upper side of the lengths of tube.

With a device of this kind, it is possible to regulate the discharge aperture in the filler head very precisely or to close it immediately if necessary. Such a filler head also has the advantage that when the discharge aperture is made smaller the granular filter material normally used is not crushed to form undesirably dusty material.

What we claim is:

l.v A device for the manufacture of cigarette filters within which sections of fibrous and free-running filter materials are arranged in succession, including a filler head (16) for feeding free-running filtration material into spaces (17) situated between filter elements or wads arranged on a filter-tip cover strip with which the wads travel continuously forwards,

a storage container (18) being provided with a discharge slot (20) of which constitutes a filling aperture;

which device further comprises a shut-off arrangement, including a scoop-shaped closing member (33) having a closing edge, said arrangement operating in conjunction with said discharge slot (20) in the filler head (16) so as to regulate the opening of that slot,

the bottom portion (32) of the -storage container (18) being cylindrical and having a longitudinal axis (37),

the shut-off arrangement comprising said scoopshaped closing member (33) in contact with the inner face of cylindrical bottom (32) of storage container (18) and capable of rotation about the longitudinal axis thereof, the closing edge of the closing member (33) running helically about the longitudinal axis (37) of said cylindrical portion (32) of the storage container, whereby when the closing member (33) turns in the closing direction it is initially the end of the discharge slot (20) that faces the opposite way to the direction of travel of the spaces (17) to be filled which is freed, this being followed by those parts of the discharge slot which are farther from the said end thereof as the closing member continues to turn.

2. A device as claimed in claim 1 which further prises means for providing a continuous supply of a succession of filter elements or wads (l and 2), uniformly spaced, on a continuously fed filter-tip cover strip means (12-14) for securing the individual filter wads (l and 2) to the cover strip,

means (15) for guiding and conveying the cover strip and its attached filter wads and continuously moving them forward;

a shaping member (25), in operative association with said guiding and conveying means, by which the cover strip, as it moves forward, is wrapped at least approximately U-fashion around the filter wads (l and 2) attached to it;

a sliding member (19) above the guiding and conveying means (15), and disposed between the arms of the U-shaped cover strip (3), in contact with the tops of filter wads (l and 2) moving forward with comfilter material, with the edges of the cover strip overlapping, said guide being provided with a suction device (45) for the removal of any freerunning filter material remaining between the edges of the strip;

means (46) for joining together the overlapping edges of the cover strip; and

means (51) whereby the tube filled with sections consisting of filter wads (1 and 2) and free-running filter material can be divided into sections of given length.

3. A device as claimed in claim 1, in which the storage container (18) is entered by at least one length of pipe (39), one end of which can be placed in communication with a feed pipe for the free-running filter material and the other end of which is situated at the filling level in the storage container.

4. A device as claimed in claim 1, in which the filler head (16) has resilient suspension, (24), so that it can be caused to vibrate in the direction of filling, and is connected to a vibrator (23) so as to be acted upon by it.

5. A device as claimed in claim 4, in which the resilient suspension consists of at least one fiat spring (24), the amplitude of vibration being regulated by means of an adjustable stop (29).

6. A device as claimed in claim 1; in which the filler head (16) has an elongated sliding member (19) extending in the direction of travel of the filter wads and having a sliding face which provides sealing contact with the tops of the filter wads as they move forward with the cover strip (3); in which the width of the sliding member (19) is at least approximately equal to the diameter of the filter wads (l and 2) to be wrapped in the cover strip (3); and in which the side faces (19a and 19b) of the sliding member (19) are parallel to each other and to the direction of travel of the cover strip (3) and provide sealing contact with those faces (3a and 3b) of the arms of the U-shaped cover strip which face toward each other.

7. A device as defined in claim 4, in which the vibrator (23) is operable to set the filler head (16) in vibration in the direction of filling at a frequency of 100 cycles per second.

8. A device as claimed in claim 1 which further comprises means for providing a continuous supply ofa succession of filter elements or wads (1 and 2), uniformly 8 spaced, on a continuously fed filter-tip cover strip (3);

means (12-14) for securing the individual filter wads (l and 2) to the cover strip;

means (15) for guiding and conveying the cover strip and its attached filter wads and continuously moving them forward;

a shaping member (25), in operative association with said guiding and conveying means, by which the cover strip, as it moves forward, is wrapped at least approximately U-fashion around the filter wads (l and 2) attached to it;

a sliding member (19) above the guiding and conveying means (15) and disposed between the arms of the U-shaped cover strip (3), in contact with the tops of filter wads (l and 2) moving forward with the latter, this sliding member being provided with the discharge slot of the filler head (16);

a guide (43, 44) by which the cover strip is formed into a tube completely enclosing the filter wads and the spaces between them filled with free-runing filter material, with the edges of the cover strip overlapping, said guide being provided with a suction device (45) for the removal of any free-running filter material remaining between the edges of the strip;

means (46) for joining together the overlapping edges of the cover strip;

the means for joining together the overlapping edges of the strip incorporating a first heatable element (47), which can be brought down on to the tube that is to be joined, said heatable element (47) having a guidance channel (48) at least approximately semi-circular in section, its radius of curvature being the same as the outside radius of the tube that is to be produced, said guidance channel (48) being immediately followed by a second channel (49) in a cooling unit (50) which can be lowered on to the tube so as to cause the heat-softened plastics to set; and

means (51) whereby the tube filled with sections consisting of filter wads (l and 2) and free-running filter material can be divided into sections of given length.

9. A device as claimed in claim 8, in which, beyond the first heatable element, considered with respect to the'direction of motion of the guiding and conveying means, is a second heatable element, the guidance channel (62) of which cements the as yet uncemented portion of the strip (3) formed into a tube to the filter wads. 

1. A device for the manufacture of cigarette filters within which sections of fibrous and free-running filter materials are arranged in succession, including a filler head (16) for feeding free-running filtration material into spaces (17) situated between filter elements or wads arranged on a filter-tip cover strip with which the wads travel continuously forwards, a storage container (18) being provided with a discharge slot (20) of which constitutes a filling aperture; which device further comprises a shut-off arrangement, including a scoop-shaped closing member (33) having a closing edge, said arrangement operating in conjunction with said discharge slot (20) in the filler head (16) so as to regulate the opening of that slot, the bottom portion (32) of the storage container (18) being cylindrical and having a longitudinal axis (37), the shut-off arrangement comprising said scoop-shaped closing member (33) in contact with the inner face of cylindrical bottom (32) of storage container (18) and capable of rotation about the longitudinal axis thereof, the closing edge of the closing member (33) running helically about the longitudinal axis (37) of said cylindrical portion (32) of the storage container, whereby when the closing member (33) turns in the closing direction it is initially the end of the discharge slot (20) that faces the opposite way to the direction of travel of the spaces (17) to be filled which is freed, this being followed by those parts of the discharge slot which are farther from the said end thereof as the closing member continues to turn.
 2. A device as claimed in claim 1 which further comprises means for providing a continuous supply of a succession of filter elements or wads (1 and 2), uniformly spaced, on a continuously fed filter-tip cover strip (3); means (12-14) for securing the individual filter wads (1 and 2) to the cover strip; means (15) for guiding and conveying the cover strip and its attached filter wads and continuously moving them forward; a shaping member (25), in operative association with said guiding and conveying means, by which the cover strip, as it moves forward, is wrapped at least approximately U-fashion around the filter wads (1 and 2) attached to it; a sliding member (19) above the guiding and conveying means (15), and disposed between the arms of the U-shaped cover strip (3), in contact with the tops of filter wads (1 and 2) moving forward with the latter, this sliding member being provided with the discharge slot of the filler head (16); a guide (43, 44) by which the cover strip is formed into a tube completely enclosing the filter wads and the spaces between them filled with free-running filter material, with the edges of the cover strip overlapping, said guide being provided with a suction device (45) for the removal of any free-running filter material remaining between the edges of the strip; means (46) for joining together the overlapping edges of the cover strip; and means (51) whereby the tube filled with sections consisting of filter wads (1 and 2) and free-running filter material can be divided into sections of given length.
 3. A device as claimed in claim 1, in which the storage container (18) is entered by at least one length of pipe (39), one end of which can be placed in communication with a feed pipe for the free-running filter material and the other end of which is situated at the filling level in the storage container.
 4. A device as claimed in claim 1, in which the filler head (16) has resilient suspension, (24), so that it can be caused to vibrate in the direction of filling, and is connected to a vibrator (23) so as to be acted upon by it.
 5. A device as claimed in claim 4, in which the resilient suspension consists of at least one flat spring (24), the amplitude of vibration being regulated by means of an adjustable stop (29).
 6. A device as claimed in claim 1, in which the filler head (16) has an elongated sliding member (19) extending in the direction of travel of the filter wads and having a sliding face which provides sealing contact with the tops of the filter wads as they move forward with the cover strip (3); in which the width of the sliding member (19) is at least approximately equal to the diameter of the filter wads (1 and 2) to be wrapped in the cover strip (3); and in which the side faces (19a and 19b) of the sliding member (19) are parallel to each other and to the direction of Travel of the cover strip (3) and provide sealing contact with those faces (3a and 3b) of the arms of the U-shaped cover strip which face toward each other.
 7. A device as defined in claim 4, in which the vibrator (23) is operable to set the filler head (16) in vibration in the direction of filling at a frequency of 100 cycles per second.
 8. A device as claimed in claim 1 which further comprises means for providing a continuous supply of a succession of filter elements or wads (1 and 2), uniformly spaced, on a continuously fed filter-tip cover strip (3); means (12-14) for securing the individual filter wads (1 and 2) to the cover strip; means (15) for guiding and conveying the cover strip and its attached filter wads and continuously moving them forward; a shaping member (25), in operative association with said guiding and conveying means, by which the cover strip, as it moves forward, is wrapped at least approximately U-fashion around the filter wads (1 and 2) attached to it; a sliding member (19) above the guiding and conveying means (15) and disposed between the arms of the U-shaped cover strip (3), in contact with the tops of filter wads (1 and 2) moving forward with the latter, this sliding member being provided with the discharge slot of the filler head (16); a guide (43, 44) by which the cover strip is formed into a tube completely enclosing the filter wads and the spaces between them filled with free-runing filter material, with the edges of the cover strip overlapping, said guide being provided with a suction device (45) for the removal of any free-running filter material remaining between the edges of the strip; means (46) for joining together the overlapping edges of the cover strip; the means for joining together the overlapping edges of the strip incorporating a first heatable element (47), which can be brought down on to the tube that is to be joined, said heatable element (47) having a guidance channel (48) at least approximately semi-circular in section, its radius of curvature being the same as the outside radius of the tube that is to be produced, said guidance channel (48) being immediately followed by a second channel (49) in a cooling unit (50) which can be lowered on to the tube so as to cause the heat-softened plastics to set; and means (51) whereby the tube filled with sections consisting of filter wads (1 and 2) and free-running filter material can be divided into sections of given length.
 9. A device as claimed in claim 8, in which, beyond the first heatable element, considered with respect to the direction of motion of the guiding and conveying means, is a second heatable element, the guidance channel (62) of which cements the as yet uncemented portion of the strip (3) formed into a tube to the filter wads. 